The International Atomic Energy Agency (IAEA) says Iran's nuclear activities have remained within key limits of Tehran's 2015 nuclear deal with world powers -- despite growing economic pressure from U.S. sanctions reimposed after President Donald Trump withdrew the United States from the accord.

The United Nations' nuclear watchdog, which monitors Iran's nuclear activities under the 2015 agreement, said in a quarterly report that Iran stayed within the accord's uranium-enrichment limits and complied with limitations on its stock of enriched uranium.

The report was distributed to IAEA member states on February 22 and reviewed by Western news agencies.

IAEA inspectors also said in the report that they did not find any irregularities related to Iran's Arak nuclear research reactor, which originally was designed to produce plutonium as a by-product.

Under the 2015 nuclear deal, Iran significantly limited its nuclear program in exchange for relief from international economic sanctions.

But Washington has reimposed tough sanctions on Tehran after Trump withdrew from the deal in May 2018.

Other signatories to the nuclear deal -- Germany, France, Britain, China, Russia, and the European Union -- have been have been working to keep it alive and have resisted U.S. pressure to abandon the accord.